utils: add has_fs_type() + is_fs_type()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

src/lxc/utils.c

@@ -2383,3 +2383,25 @@ void *must_realloc(void *orig, size_t sz)
 
 	return ret;
 }
+
+bool is_fs_type(const struct statfs *fs, fs_type_magic magic_val)
+{
+	return (fs->f_type == (fs_type_magic)magic_val);
+}
+
+bool has_fs_type(const char *path, fs_type_magic magic_val)
+{
+	bool has_type;
+	int ret;
+	struct statfs sb;
+
+	ret = statfs(path, &sb);
+	if (ret < 0)
+		return false;
+
+	has_type = is_fs_type(&sb, magic_val);
+	if (!has_type && magic_val == RAMFS_MAGIC)
+		WARN("When the ramfs it a tmpfs statfs() might report tmpfs");
+
+	return has_type;
+}

src/lxc/utils.h

@@ -36,6 +36,7 @@
 #include <linux/loop.h>
 #include <sys/syscall.h>
 #include <sys/types.h>
+#include <sys/vfs.h>
 
 #include "initutils.h"
 
@@ -386,4 +387,9 @@ char *must_copy_string(const char *entry);
 /* Re-alllocate a pointer, do not fail */
 void *must_realloc(void *orig, size_t sz);
 
+/* __typeof__ should be safe to use with all compilers. */
+typedef __typeof__(((struct statfs *)NULL)->f_type) fs_type_magic;
+bool has_fs_type(const char *path, fs_type_magic magic_val);
+bool is_fs_type(const struct statfs *fs, fs_type_magic magic_val);
+
 #endif /* __LXC_UTILS_H */